This application claims priority under 35 U.S.C. xc2xa7xc2xa7119 and/or 365 to patent application Ser. No. 0100251-8 filed in Sweden on Jan. 30, 2001.
1. Technical Field of the Invention
The present invention relates to a tool holder for cutting inserts for chip removing machining, the tool holder comprising a head on which is disposed an insert seat. The seat includes an insert-support surface and side surfaces arranged to engage side edges of the cutting insert when the cutting insert is clamped in the seat. One of the side surfaces is flexible.
2. Prior Art
In a leaflet from ISCAR, entitled xe2x80x9cISCAR""s New Clamping System for Profiling Toolsxe2x80x9d prior art is shown, which is illustrated herein in FIGS. 6 and 7, as well as a further development of prior art, which is illustrated in FIG. 8 herein.
As is seen in FIGS. 6 and 7, in the prior art there is disclosed a three-point abutment. In case the cutting insert S is exposed to a force Fc1 acting from the right, see FIG. 6, the cutting insert S will abut at two points CP1 and CP2 against a stiffer side surface 100 of a holder 102 and at one point CP3 against a more resilient side surface 104. This is illustrated in FIG. 6 by an angle xcex41 formed between the cutting insert S and the more resilient side surface.
If the force Fc2 acting on the cutting insert S comes from the left, see FIG. 7, the cutting insert S will abut against the stiffer side surface at one point CP1 and at two points CP3 and CP4 against the more resilient side surface. This is illustrated in FIG. 7 by an angle xcex42 formed between the cutting insert S and the stiffer side surface.
Clamping of the cutting insert S is normally effected with a so-called rocking pin 106, possibly in combination with a top clamp. This has turned out to be insufficient in a number of applications, i.e., the position of the cutting insert is not fixed in the holder to a sufficiently high degree of accuracy. This is particularly valid for this elongated type of cutting insert where large movements of the insert occurs if the cutting insert is exposed to varying loads from differing directions, which is the case during, for instance, copy turning.
As is seen in the prior art illustrated in FIG. 8, the insert seat is provided with a self-adjusting wedge W which abuts against a side surface of the cutting insert, the wedge being movable and self-adjusting to the cutting insert so that a four-point abutment CP1, CP2, CP3, CP4 is obtained. Since the self-adjusting wedge is movable, the fixation of the cutting insert in the insert seat will also in this case be inadequate for certain applications.
A turning tool having a replaceable indexable insert is previously known from DE 37 14 055. In an embodiment of a turning tool according to DE 37 14 055, a flat wedge abutting against the indexable insert is provided with a slot, in which a tightening screw is applied. The flat wedge abuts against the indexable insert at two contact points. The slot has an open end that faces the side of the flat wedge that is free, i.e., is turned outwards. By activating the tightening screw, the slot may be widened, whereby the abutment of the contact points against the indexable insert may be adjusted. A disadvantage of this known turning tool is that if the side surface of the insert seat that is integrated with the turning tool in question is damaged or becomes worn out, the entire turning tool has to be replaced, which is disadvantageous from the point of view of costs. As for the forces being transferred from the indexable insert to the two contact points of the flat wedge, the force is greatest at the contact point which is situated closest to the center of the indexable insert. This force will propagate in the flat wedge and then act on the part of the slot that includes the open end. It is true that a screw is applied in the slot but the arrangement entails that the screw should transmit the force in question only by linear contact with the sidewalls of the slot. Due to the fact that the surface pressure between slot and screw can become exceptionally high, there is an obvious risk that a certain deformation of the flat wedge in contact with the screw may occur.
Aims and Features of the Invention
A primary aim of the present invention is to provide a tool holder of the above-mentioned kind, where an exceptionally accurate fixing of the cutting insert in the insert seat is obtained, notwithstanding the fact that the cutting insert is exposed to varying loads and/or loading directions during, for instance, copy turning. The consequence of this is increased dimensional precision during use of the tool holder.
Yet another aim of the present invention is to ensure that the cutting insert is fixed in the insert seat by means of a so-called four-point abutment.
Another aim of the present invention is to ensure that certain readjustments of the insert seat should be possible in connection with wear of the same.
The present invention relates to a tool holder for mounting a cutting insert for chip removing machining. The holder comprises a head on which is disposed an insert seat that includes an insert-support surface. A plate-shaped member is detachably mounted on the head and includes first and second fingers. The fingers include respective first and second side surfaces forming a recess therebetween. The first and second side surfaces are arranged in upstanding relationship with the insert-support surface to define therewith the seat. The first finger includes a slot and is thus rendered flexible, wherein the first side surface is elastically displaceable relative to the second side surface. Each of the first and second side surfaces includes a recess formed therein at a location intermediate opposite ends of the respective first and second side surfaces, wherein each of the first and second side surfaces defines spaced-apart contact areas. The through-slot includes a cavity receiving a screw which is adjustable to displace the first side surface.
Preferably, the plate-shaped member includes a first surface facing a second surface of the tool holder. The first and second surfaces include serrations disposed in meshing relationship, except at a location permitting the first finger to be elastically displaced relative to the second finger.